Not strictly matching your criteria (see below) but maybe suitable for the more dangerous systems would be the Asp MkII.
According to the original elite manual...

Intended for reconnaissance and the transport of high-ranking military personnel from combat

Good thought, I was planing to use the Asp Mark II as an escort but thanks to gsagostinho's Texture Pack: Asp Mk II there are plenty of appearances to chose from, so using it as main craft for some systems makes much sense.

Trying to survive behind the controls of a Caduceus Psi XT in Alpha test

Well, it took a while to catch up with old ideas, however since I am on sick leave 3 h flight from home it seems now I have plenty of time to continue working on my code.

Zerstörer and Commissar Limousine are logical choices if the relevant OXZ's are installed.

I struggle with Anarchy, for my believing no government, the systems are run by warlords, criminals and "influential" person and organizations. Diplomats yes or no ?

Multi-Government is the exact opposite, a lot of leaders, united or hostile, a wide range of ships could be possible. Actually this type of government has a great potential to be improved, it seems it was always underestimated.

Dictatorships, with Dictators.oxz installed. For junta (agricultural) Python ET Special or Asp Mark II. Imperial (tech) a Mussurana would be perfect, rich and powerful leaders want to show off.

Would it make sense to get a different display color for diplomat ships, including a heavy bounty for everybody attacking ?

@cbr, do you have additional textures ? I really liked your gold variant

Trying to survive behind the controls of a Caduceus Psi XT in Alpha test